SIP_EVAL
Name
SIP_EVAL
Purpose
Compute distorted coordinates given SIP (simple imaging polynomial)
coefficients.
Explanation
See http://fits.gsfc.nasa.gov/registry/sip.html for the SIP convention
The coefficients are passed via common block. This is because this
routine is called by the intrinisc BROYDEN() function in AD2XY, and
common blocks are the only way to pass parameters to the user supplied
function in BROYDEN().
Calling Sequence
res = SIP_EVAL(xy)
Inputs
xy - 2 elements vector giving the undistorted X,Y position
Outputs
res - 2 element vector giving the distorted position
Common Blocks
common broyden_coeff,xcoeff,ycoeff
XCOEFF, YCOEFF are both nxn arrays giving the SIP coefficient for an
n x n polynomial.
Revision History
Written W. Landsman Dec 2013